The alkali refining of oils containing vitamin A

Abstract

PG 80 PG 150 PG 250 11-67 x los 8.46 x los 4'41 x 1 0 s 7'87 x 1 0 s PG 350 5.69 x loL 1'97 x 1 0 5 1.04 x 10' ppg 4.g PG 900 0.33 X lo5 ConclusionI. An investigation was made of the changes, produced by dry grinding, in the position and slope of the straight line relating to the gel strength of weak gels and the square of the pectin concentration.2. Grinding produced (a) a marked increase in the amount of material estimated as calcium pectate but not contributing to gel formation and (b) a decrease in the rate at which the strength increases with increasing pectin concentration, i.e. a decrease in the slope of the line.3. The logarithm of the slope of the line is a linear function of the limiting viscosity of the corresponding pectin determined from data for the aqueous solution of the pectin itself and for the nitro-ester in acetone solution. The slope of the line is a function of the values of Young'smodulus for the material constituting the fibrils of the gels as calculated from the formula Contrary to thc previous opinion that alkali refining reduces considcrably the vitamin A potency of fish liver oils, it has been found that under usual refining conditions the neutralization with alkalis results in increased potency. The inncasc is approximately orooortioml to the free fattv acid content of the original oil. The IO,OOO blue units er gram the loss was over so"/u.Brocklesby conckdes in his book8 : " It thus appears probable that the pigments and vitamin A are preferentially adsorbed, and due regard to this phenomenon should be taken when treating oils containing vitamin A with alkaline solutions."